This invention relates generally to ink jet printers. More particularly, the invention pertains to an ink jet device capable of firing fluid through a nozzle at relatively high speeds and at variable volumes, i.e., the ink jet device may expel just fluid, vapor, or a combination of fluid and vapor, such that the amount of ejected vapor and fluid may be modulated.
Ink jet recording is a method of forming ink droplets by discharging recording fluid (e.g., ink) from an orifice provided in a recording head. The ink droplets adhere to a recording medium (e.g., paper) by being xe2x80x9cfiredxe2x80x9d at the recording medium. Devices operating an ink jet recording method typically utilize impulse fluid or ink jets designed and driven to eject a droplet of recording fluid through an orifice of the ink jet. In general, it is unnecessary to operate ink jet devices at high performance levels, i.e., at high velocities and long throw distances. However, it has been found that many applications, including industrial applications, require high-performance ink jet devices. In one respect, in various industrial ink jet applications, the print medium may be located some distance from the ink jet orifice. To maintain a relatively small droplet size and create a high resolution dot on the print medium in these types of applications, it is relatively important for the ink jet devices to be operated at high-performance levels.
In addition to the above, it is advantageous to control the amount of ink volume and vapor volume, such that the dot formed on the print medium from the ink droplet may have an additional amount of controllability.
Conventional ink jet recording devices, however, suffer from a variety of drawbacks and disadvantages. For example, FIG. 1, which depicts a conventional thermal ink jet recording device (U.S. Pat. No. 4,459,600, issued to Sato et al.), shows a recording head 1, having a supply of liquid 3 being provided by an external liquid feeding device through a liquid feeding path 6 at a pressure P. In this figure, the pressure P is not sufficient to discharge the liquid from a discharge orifice 2. A heat generating body 4, an expedient to generate heat energy, is positioned in a heat acting zone 5, where the generated heat energy acts on the liquid 3. The liquid 3 in the heat acting zone 5 undergoes changes in its state (liquid volume expansion or generation of foams) effective to discharge the formed droplets through a liquid discharge path 7. That is, the heat generating body 4 typically generates sufficient heat to change the state of the liquid 3 in the heat acting zone 5 to create sufficient pressure to eject a certain amount of liquid through the discharge orifice 2.
As illustrated in FIG. 1, the amount of liquid 3 supplied and maintained in the liquid discharge path 7 generally represents the amount of liquid to be ejected through the discharge orifice 2. In this respect, the amount of liquid ejected through discharge orifice 2 remains relatively constant for each amount of liquid ejected. Thus, because the amount of liquid in the liquid discharge path 7 remains substantially constant, the recording head 1 illustrated in FIG. 1, is not capable of modulating the amount of liquid ejected through the discharge orifice 2.
Other conventional types of recording heads utilize a similar design to that described above to alter the phase of the liquid to create sufficient pressure for liquid positioned in front of the altered liquid to be ejected through an orifice. Examples of conventional types of thermal recording heads include, U.S. Pat. No. 4,716,418, issued to Heinzl et al., U.S. Pat. No. 5,708,466, issued to Noguchi, and U.S. Pat. No. 6,126,259, issued to Stango et al. These conventional types of recording heads all suffer from the same or similar disadvantages as noted above with respect to FIG. 1. For example, none of these types of recording heads enables a variable amount of liquid to be ejected from the recording head. More specifically, all of the above cited types of recording heads are operable to eject only that amount of liquid positioned between the heat generating element and a discharge orifice.
In accordance with the principles of the present invention, an ink jet device includes a first fluid path, a second fluid path, and a discharge opening through which a printer fluid is configured to be ejected from the ink jet device. The discharge opening is located between the first fluid path and the second fluid path. The ink jet device also includes at least one heat generating element located in the first fluid path for heating the printer fluid in the first fluid path, and a first closure device for substantially impeding a flow of the printer fluid through the second fluid path.
According to another aspect, the present invention pertains to a method of recording on a printing medium. According to the method, a first fluid path and a second fluid path are substantially filled with printer fluid. At least one heat generating element located in the first fluid path is activated to heat and substantially vaporize a first portion of the printer fluid located in the first fluid path. A second portion of the printer fluid travels towards the second fluid path in response to the first portion of the printer fluid becoming heated and vaporized. In addition, a flow of the printer fluid through the second fluid path is substantially impeded to thereby cause at least a portion of the printer fluid to be ejected through a discharge opening located between the first fluid path and the second fluid path.
In accordance with yet another aspect, the present invention pertains to a method for modulating a characteristic of a printer fluid ejected from an ink jet device. According to the method, a printer fluid is heated to cause a first portion of the printer fluid to become heated and vaporized. The vaporized first portion thus creates a predetermined amount of pressure within a first fluid path of the ink jet device, thereby causing a second portion of the printing fluid to be forced toward a second fluid path of the ink jet device. Additionally, the flow of the printer fluid in the second fluid path is substantially impeded at a predetermined time after the heating step to thereby cause at least a portion of the printer fluid to be ejected through a discharge opening located between the first and second fluid paths.
By virtue of the configuration and manner by which the printer fluid in an ink jet device according to the principles of the present invention may be operated, various advantages may be obtained by practicing various aspects of the present invention. For example, high pressure colored steam or ink vapor may be used to print light colors, accelerate drying time of the printed output, etc. Additionally, vapor ejection may be used in other processes in the printing industry, e.g., surface treatments, micro humidity control, to clean/purge small instruments, etc. Thus, certain aspects of the present invention are configured to overcome certain drawbacks and disadvantages associated with known ink jet printer devices.